The role of Mg2+ ions in the corrosion behaviour of AA2024-T3 aluminium alloys immersed in chloride-containing environments

作者：Collazo A; Novoa X R; Perez C^*

来源：Electrochimica Acta, 2014, 124: 17-26.

DOI：10.1016/j.electacta.2013.10.130

• AA2024-T3 alloy
• Cathodic inhibitor
• S phase particles
• Mg dealloying process

It is well-known the harmful impact of chloride ions in the corrosion behaviour of aluminium and its alloys. The present work investigates the use of Mg2+ ions as corrosion inhibitors of AA2024-T3 samples immersed in chloride-containing electrolytes. %26lt;br%26gt;AA2024-T3 samples were immersed into an electrolyte containing chloride ions, in absence or presence of Mg2+. The electrochemical behaviour was studied by potentiondynamic polarization and electrochemical impedance spectroscopy techniques. The results showed the beneficial effects afforded by the Mg2+ ions. First, the open circuit potential was shifted towards more cathodic values and, on the other hand, the impedance values obtained for samples tested in presence of Mg2+ were higher, suggesting a slowdown of the corrosion rate. The morphological characterization was performed using scanning electron microscopy and energy dispersive X-ray spectroscopy. The results demonstrated that the presence Mg2+ hinders Mg dealloying of the S phase particles, which delays their change from anodic to cathodic behaviour, so delaying the subsequent Al matrix galvanic attack. An additional protection mechanism is related to the blockage of cathodic areas by the precipitation of Mg(OH)(2) in alkaline environments.

• 出版日期2014-4-1